Fiber glass is commonly used as filler, or a reinforcing agent, in polycarbonates to improve stiffness (modulus) and dimensional stability (coefficient of thermal expansion). Typical glass fiber loadings in polycarbonates range from 5 to 50%. As the fiber glass content increases, the polycarbonate exhibits a decrease in melt flow characteristics and an increase in melt viscosity. As a result, it is difficult to generate thin-wall injection molded parts (thickness<1.0 mm) with these kinds of polycarbonate materials. In addition, increasing fiber glass content results in increased surface roughness and lower surface gloss in injection molded parts due to glass fibers breaking through the resin surface.
The use of fiber glass-filled polycarbonates in applications such as mobile phones and portable electronics housings is increasing as design trends move toward thinner wall housings and frames requiring higher stiffness materials. However, the relatively poor surface appearance in glass-filled polycarbonates limits their use in applications that require high surface gloss or a secondary painting or metallization step.
Based on these demands there exists a need for a high-flow glass-filled material to effectively fill a thin-wall article and obtain a high gloss surface to achieve a certain appearance or allow for a secondary paint or metallization step.